Furnace



FURNACE.

APPLICATION FILED JUNE 2s, Is'zo.

1,417,829 Patented May 305 1922.

UNITED STATES PATENT OFFICE.

HENRY JOHNSON, OF WINSTON-SALEIVI, NORTH CAROLINA, ASSIGNOR TO THE SOUTHERN IRON & STEEL CORPORATION, A. CORPORATION OF NORTH CARO- LINA.

FURNACE.

Application filed June 28,

fo all eli/tom t may concern:

Be 1t known that I, HENRY Jonsson, subject of the Ylfing of Great Britain, residing` at vVl/vinston-Salem, in the county of Forsyth and State of North Carolina, have invented certain new and useful Improvements in Furnaces, of which the following is a specification.

Wy invention relates to a furnace for heating tobacco barns in which tobacco is being cured. The construction of the furnace and its mode of use will be readily understood from the accompanying dra-wings in which- Fig. l is an end elevation.

Fig. 2 ay transverse section.

"Fig 3 is a longitudinal section on plane 3 3 of Fig. l; and

Fig. 4: is a horizontal section on plane 4 4. of Fig. e.

The furnace is preferably made as a whole out of metal, so that it can be transported and set up in the tobacco barn without the necessity of assembling the various parts.

The exterior wall l and the interior wall 2 are spaced apart to form an air-space. which may either be used as a dead-airspace for heat insulation purposes only, or may be provided with an inlet and an outlet for circulation of air therethrough to furnish a supply of heated air to the interior of the barn. IVithin the chamber formed by the interior wall 2 is provided a grate 3, adapted to burn either coal or wood. Doors 4, 4 are provided for feeding fuel to the grate, and doors 5, 5 control the admission of air to the ash-pit 6. Air openings 2O are preferably provided in these doors.

The products of combustion pass over a fire-bridge 7, and then downwardly into a chamber 8, the exit iue 9, for products of combustion being located as near as possible to the lower end of this chamber 8.

This location of the exit flue is one feature of my invention, and has the important advantage that this exit flue, is brought near to the level of the barn door on which the furnace rests. As is usual in furnaces of this type, a. series of flues (not shown herein) are connected to the exit flue of the furnace and extend over the iioor of the barn in order to insure a thorough heating of the air; and these flues can thus be easily stepped over.

In order to better control the draft of the furnace, I provide pipes 10, 10, extending on each side of the furnace and opening into Specification of Letters Patent.

1920. Serial N0. 392,454.

the chamber 8, near the bottom. These pipes are provided at their outer ends with registers or dampers Il, l1, by which the quantity of air admitted can be controlled. I have found that, while the draft can' be controlled by opening and closing the doors 5, 5 to the ash-pit, the result is, when these doors are tightly closed to exclude all airsupply to the ash-pit, that there is a very marked tendency to so overheat the bais that they soon become useless, unless they are made of very considerable size and correspondingly great weight. To eliminate this diflieulty, I provide the valve controlled pipes 10, connecting the outer air to the secondary chamber 8, in proximity to the opening of the exit flue 9. By opening the dampers 1l, Il, the suction draft or partial vacuum due to the draft, is lessened. Suflicient air can then be admitted to the ashbox to keep the lower surfaces of the gratebars cool, while there is not sufficient draft to cause a too intense combustion of the fuel on the grate bars. The cooler air admitted through pipes l0 into the chamber 8 and exit flue 9 also serves to lower the temperature of the gases passing through this flue. I am thus enabled to readily control the temperature of the outgoing gases and at the same time am enabled to use relatively light grate-bars, which is of particular advantage in this type of furnace, which is designed to be portable.

In curing tobacco, after the leaves have been subjected to the proper heating conditions to dry and color the leaves, it is necessary to order the tobacco, so that the leaves will be sufliciently pliable to permit further handling. rl'his ordering I accomplish by providing means for furnishing and delivering steam under slight pressure into the atmosphere of the barn. For this purpose, I provide pipes l2 passing through the fire-box, and connected to a manifold 12, to which water is delivered under some pressure as from'an elevated tank 13. At the other end the pipes l2 are connected to a steam dome or header 14, from which the steam escapes through pipe l5. A flexible hose (not shown) enables the steam to be delivered to any desired part of the barn.

The steam pressure is controlled by any suitable pressure-relief valve 16. A steam pressure of from one pound upward has been found desirable in practice. I thus provide a simple, compact, furnace having adequate means for controlling the temperatures o1c thev heating fines; for providing steam for ordering; and for maintaining the life of the grate-bars.

The steam-generating pipes l2 may be either permanently or detachably connected to the furnace casing. By suitably arranging the couplings, the whole steam supply system may readily be removed and replaced.

The steam-generating pipes may also, if desired, extend downward into the secondary chamber 8.

A furnace for curing tobacco comprising in one portable structure made of metal, an exterior longitudinal wall, an interior longitudinal wall, and transverse end walls together forming an enclosed air chamber, the chamber formed by the inner wall and end walls having near one end a fire bridge extending upwardly from the bottom of the furnace and spaced Jfrom the rear end wall to form a secondary chamber, a grate supported on the fire bridge and the front end wall, an exit flue located near the bottom of said secondary chamber, damper controlled air iii/ies extending from the front end of the furnace through the air chamber and opening into said secondary chamber in proximity to said exit flue, and doors opening into the spaces above and below the grate.

In testimony whereoi a'fiix my signature.

HENRY JOHNSON. 

